Within the scope of the invention, a macroactuator is any actuator that cannot be manufactured by a micromachining process and which can therefore not be integrated in a micromachined device where an actuator is needed.
The invention also concerns a micropipetting module which comprises such a coupling system.
European Patent Application EP-A 0865824 A1 describes a micromachined pipetting device wherein a membrane is moved by means of a micromachined electrostatic actuator. With this kind of actuator it is difficult to produce forces which are sufficiently large as to displace the membrane with sufficient precision, in particular when the size of the membrane and the size of the necessary deflection of the membrane have to be increased in order to be able to increase the volume to be pipetted. With exception of thermal actuated micromechanical actuators, the strongest force that can be applied on the membrane with a micromechanical actuator is about one Newton. In order to overcome this limitation, it has been therefore proposed to use a macroactuator, e.g. a piezo-electric actuator, to effect the necessary deflection of the membrane of a micromachined pipetting device. Up to now a conventional approach proposed for this purpose has been to bond one end of the macroactuator to the membrane, e.g. by gluing that end to the membrane. Such a bonding is however disadvantageous, because it strongly limits flexibility of design of a pipetting module consisting of a micromachined pipetting device and a macroactuator connected thereto.
A first aim of the invention is to provide a system for coupling a macroactuator to a movable element of a micromachined device. The coupling system makes possible the positioning of the macroactuator with high precision with respect to the movable element and the transmission of the required large forces of a macroscopic actuator to that movable element for a precise and accurate large displacement thereof in order that that displacement can be effected with high accuracy and precision. Furthermore the coupling system should provide more flexibility for the overall design of a device which substantially consists of the micromachined device and of a macroactuator coupled thereto. A second aim of the invention is to provide a micropipetting module which comprises a coupling system according to the invention.